INFLUENCE OF HIGH PRESSURE TORSION ON THE MICROSTRUCTURE AND MECHANICAL PROPERTIES OF BIOSOLUBLE ZINC ALLOY ZN-0.8%LI

Abstract

A study on the formation of a grain structure in the zinc alloy Zn-0.8% Li by the method of high pressure torsion (HPT) has been made. It has been shown that the use of HPT leads to a significant refinement of the average grain size to 850 nm (compared to the homogenized state). Tensile tests have been carried out. As a result of the studies, it has been found that the refinement of the grain structure during HPT contributed to an increase in microhardness by 15% compared to the homogenized state. HPT specimens showed high strength values at room temperature. The maximum tensile strength of745 MPa was obtained on HPT specimens at a tensile rate of 10–2s–1. We also analyzed the change in the value of the velocity sensitivity m of the samples after the formation of a grain structure during HPT. As follows from the results of the experiment, the maximum speed sensitivity coefficient m = 0.41 indicates signs of grain boundary slippage and manifestation of the superplasticity effect at strain rates of 1×10–3 – 5×10–4s–1. The maximum plasticity value of 125% was achieved at a strain rate of 10–4. The obtained values of mechanical characteristics are 2 times higher than required for use as medical implants.